For a working machine cooling control system to date, Japanese Unexamined Patent Application Publication No. 2007-255216 is known. The working machine cooling control system of Japanese Unexamined Patent Application Publication No. 2007-255216 is furnished with a control device that controls the rpm of a cooling fan that introduces external air as a cooling blast for cooling a cooling fluid, wherein the system calculates the difference between a fluid-temperature sensor that senses the fluid temperature and an atmospheric temperature sensor that senses the temperature of the external air, and sets a target rpm for the cooling fan corresponding to the size of the difference.